ObjectiveTo study SCN1A gene mutations and their inheritance in patients with Dravet syndrome (DS), and to analyze the phenotypes of their family members. MethodsGenomic DNA was extracted from peripheral blood samples from DS patients and their parents. SCN1A gene mutations were screened using PCR-DNA sequencing and multiplex ligation-dependent probe amplification (MLPA). Results547 DS patients were collected, SCN1A gene mutations were identified in 379 patients (69.3%), which included 179 missense mutations (47.2%), 78 nonsense mutations (20.6%), 77 frameshift mutations (20.3%), 37 splice site mutations (9.8%), and 8 cases with SCN1A gene fragment deletions or duplications (2.1%). Of 379 DS patients, the parents of 354 DS patients were further analyzed, the de novo mutations accounted for 92.9%, inherited mutations accounted for 7.1%, and in 5 of the latter families, the SCN1A-positive parent carried a somatic mutations mosaicism. For the 25 parents carrying SCN1A mutations, 1 had DS, 11 had febrile seizures plus, 9 had febrile seizures, whilst 4 were normal. ConclusionsThe mutation rate of SCN1A in DS patients is high. Most mutations are of missense and truncation mutations (including nonsense mutation and frameshift mutation). Only a few patients have carried fragment deletions or duplications. Most SCN1A mutations are de novo, only a few are inherited from the parents. SCN1A mutations carried by the parents can be in the form of mosaicism. The phenotypes of parents with SCN1A mutations can be severe, mild or normal, and a mosaic transmitting parent always shows mild or normal.
Objective To measure and compare the difference between the normal control and retinoschisis with multifocal electroretinography. Methods Nineteen cases (21 eyes) of normal control and 8 cases (15 eyes) of inherited retinoschisis were measured with VERIS ScienceTM 4.0.Three cases (6 eyes) of inherited retinoschisis were tested with Ganzfeld ERG. Results There was statistically significant difference of average response density and latencies in all 6 ring retinal regions between the normal control and retinoschisis. The topography of multifocal ERG showed that multifocal amplitude decreased with disappearing or decreasing of central peak amplitude in patients with retinoschisis. The P1/N1ratio of the multifocal ERG average response densities in 6 ring retinal regions was different from the b/a ratio of the Ganzfeld ERG. Conclusion Each of the multifoca l ERG and Ganzfeld ERG has its advantage in the diagnosis of the retinoschisis. (Chin J Ocul Fundus Dis, 2001,17:268-270)
Inherited retinal degeneration (IRD) is a group of fundus diseases characterized by a high degree of genetic heterogeneity and clinical heterogeneity, and more than 300 genetic mutations have been identified in association with IRD. Dysregulation of the intracellular second messenger cyclic guanosine monophosphate (cGMP) plays an important role in the development of IRD. cGMP participates in phototransduction process in photoreceptors. Abnormally elevated cGMP over-activate protein kinase G and cyclic nucleotide-gated channel, causing protein phosphorylation and Ca2+ overload, respectively, and these two cGMP-dependent pathways may individually or collectively drive photoreceptor degenerative lesions and death; therefore, reducing cGMP synthesis and blocking downstream signaling can be considered as treatment strategies. Investigating the molecular mechanisms of cGMP dysregulation in photoreceptor degeneration may provide a more comprehensive picture of the pathogenesis of IRD, as well as ideas for finding new therapeutic targets and designing therapeutic programs.
ObjectiveTo summarize the progress in mutant gene sequences of different types of hereditary colorectal cancer.MethodThe relevant literatures about genetic mutations in hereditary colorectal cancer at home and abroad were reviewed.ResultsHereditary colorectal cancer coule be divided into two categories according to whether it was related to the germline mutations of known oncogenes. Among the known germline mutant genes, the gene of adenomatous polyposis coli (APC), MUTYH, thymidine glycol DNA glycosylase 1 (NTHL1), polymerase (DNA) epsilon, catalytic subunit (POLE), and polymerase (DNA) delta 1, catalytic subunit (POLD1) were closely related to adenomatous polyposis syndromes, mismatch repair (MMR)-related genes were related to Lynch syndrome, serine/threonine kinase 11 (STK-11) gene was related to Peutz-Jeghers syndrome, mutant genes of SMAD4 and bone morphogenetic protein receptor type 1A (BMPR1A) were found in JPS individuals, and Cowden syndrome was caused by phosphatase and tensin homology deleted on chromosome ten (PTEN) gene mutation. For colorectal cancer patients with unknown germline mutations but significant genetic characteristics (such as hyperplastic polyposis), relevant genes had also been gradually searched out, which needed further evidence.ConclusionsColorectal cancer is a malignant tumor with genetic characteristics. Compared with sporadic colorectal cancer, the time of hereditary colorectal cancer from adenoma to cancer is shorter, and the occurrence of heterogeneous tumor is also increased, but the survival rate after active intervention is higher than the sporadic one. To study the mutant gene sequences of hereditary colorectal cancer is the improvement and development of the diseases control in modern medicine.
【Abstract】ObjectiveTo review recent studies on Muir-Torre syndrome (MTS) and to improve the knowledge about MTS.MethodsThe literatures in recent years on clinic and gene research of MTS were reviewed.ResultsMTS was is a rare autosomal-dominant disorder characterized by the predisposition to both sebaceous tumors (or multiple keratoacanthomas) and internal malignancies. Gastrointestinal cancers were the most common kind of internal malignancies in MTS patients(61%)，followed by genitourinary cancers(22%). In most cases(56%)，sebaceous tumors appeared after the emergence of internal maliganancy. Both hereditary nonpolyposis colorectal cancer(HNPCC) and MTS were caused by germline mutations in the DNA mismatch repair genes. MTS patients exhibit significantly more mutations in the hMSH2 than in the hMLH1. In these cases , both internal and skin tumors showed the characteristic of high microsatellite instability(MSI).ConclusionThe presence of sebaceous tumors(or multiple keratoacanthomas) necessitates the search for internal malignancies. It is mandatory that patients with MTS, as patients with HNPCC, should be regularly followed up to search new malignancies. Evaluation and monitoring of the family members of patients are also necessary. The patients and their families should be counseled for genetic test. Sequencing the hMSH2 gene should be the prior selection of further examinations when clinical manifestations, history and laboratory tests suggest MTS.
ObjectiveTo explore the light response, retinal inflammation and apoptosis of the retinal ganglion cells (RGCs) 1 year after the new type of channelrhodopsin PsCatCh2.0 was transfected into the retina of rd1 mice. MethodsTwenty-four male rd1 mice were randomly divided into rd1 experimental group and rd1 control group, 12 mice in each group. 1.5 μl of recombinant adeno-associated virus (rAAV)2/2-cytomegalovirus (CMV)-PsCatCh2.0-enhanced green fluorescent protein (EGFP) was injected into the vitreous cavity 1 mm below the corneoscleral limbus of mice in the rd1 experimental group, and the same dose of recombinant virus was injected 2 weeks later at temporal side 1 mm below the corneoscleral limbus. One year after virus injection, the light response of RGCs expressing PsCatCh2.0 was recorded by patch clamp technique; the expression of PsCatCh2.0 in the retina was evaluated by immunofluorescence staining; the transfection efficiency of recombinant virus was evaluated by the transfection efficiency of virus and the number of RGCs. Hematoxylin-eosin staining was performed to measure the inner retinal thickness. Western blotting was used to detect the protein expression of nuclear factor (NF)-κB p65 in retina; real-time quantitative polymerase chain reaction was used to detect the relative expression of tumor necrosis factor (TNF)-α, interleukin (IL)-6 and Bax mRNA. Terminal deoxynucleotidyl transferase kit was used to observe the apoptosis of retinal cells in each group of mice. ResultsOne year after the intravitreal injection of recombinant virus, PsCatCh2.0-expressing RGCs can still generate 30 pA photocurrent. The virus PsCatCh2.0-EGFP was mainly transfected into RGCs, and partly transfected into amacrine cells, almost no transfection was seen in bipolar and horizontal cells. There were no significant differences in the number of RGCs and thickness of the inner retina between the rd1 experimental group and the rd1 control group (F=14.35, 0.05; P＞0.05), while the rd1 experimental group NF-κB p65 protein expression, TNF-α and IL-6 mRNA quantification were significantly lower than those of rd1 control group (F=4.61, 5.91, 5.78; P＜0.05). The number of red fluorescent apoptotic cells in the retina of mice in the rd1 experimental group was less than that in the rd1 control group, and the Bax mRNA expression was lower than that in the rd1 control group, and the difference was statistically significant (F=7.52, P＜0.01). ConclusionOne year after intravitreal injection of recombinant virus, the PsCatCh2.0 expressing RGCs can still generate photocurrent. Long term transfection and expression of PsCatCh2.0 has no obvious cytotoxic effect on RGCs, nor it increases the inflammatory effect of the retina of rd1 mice with retinal degeneration.
RCBTB1 gene associated hereditary retinopathy is an extremely rare inherited retinal disease (IRD) discovered recently. The mutation of RCBTB1 gene can lead to a variety of IRD clinical phenotypes, such as early retinitis pigmentosa and delayed chorioretinal atrophy. The hereditary mode of RCBTB1 gene associated retinopathy is autosomal recessive. RCBTB1 gene plays an important role in maintaining mitochondrial function and anti-oxidative stress defense mechanism of retinal pigment epithelium cells. In the future, it is necessary to further determine whether there is a genotypic and phenotypic correlation in the age of onset of RCBTB1 gene associated retinopathy or multi-organ involvement, and evaluate the safety and efficacy of adeno-associated virus-mediated RCBTB1 gene replacement therapy in animal models, to explore the feasibility of gene replacement therapy and stem cell therapy.
The human hereditary retinal degeneration is one of the main cause of irreversible blindness in the world. the mechanisms leading to retinal photoreceptor degeneration are not entirely clear. However, microglia acting as innate immune monitors are found to be activated early in retinal degeneration in many retinitis pigmentosa animal models. These activated microglia are involved in phagocyte rod cell fragments of degenerated retina, and also produce high levels of cytotoxic substances such as pro-inflammatory cytokines and chemokines, which aggravate the death of adjacent healthy photoreceptor cells. It suggests that microglia activation plays an important role in photoreceptor degeneration. At the same time, a series of studies have confirmed that some drugs can prevent or reduce neuronal death and slow the occurrence and progression of retinal degeneration by interfering with abnormal activation of microglia. It is expected to be a new choice for the treatment of hereditary retinal degeneration.